Testing of fiber samples, such as, but not limited to, cotton, is important for determining the market value of a particular batch of material, as well as for determining a suitable usage and what processing may be required in gins or spinning mills. Today, nearly 100% of the cotton grown in the United States is classed employing testing instruments. Testing includes determining such characteristics as fiber length, as well as the content of undesired textile entities such as trash and neps.
As a relatively early example, a comb-like device for preparing a sample of ginned cotton for measuring the fiber length thereof is disclosed in Hertel U.S. Pat. No. 2,404,708, which issued in 1946. That same inventor later developed what is now known as a Hertel needle sampler, disclosed in Hertel U.S. Pat. No. 3,057,019. The Hertel needle sampler is a comb-like device arranged for movement past a perforated plate which has a fibrous mass pushed against the opposite side so that portions of the fibrous mass protrude through the perforations and are loaded onto the needles. A screw-thread based locking device then retains the fibers on the needle sampler, forming what is known in the art as a tapered beard because the fibers are of varying lengths. The tapered beard is prepared by combing and brushing to parallelize the fibers, as well as to remove loose fibers. An automated version of the Hertel needle sampler is contained within and is a major element of fiber testing apparatus, known as the Model 900A High Volume Instrument (HVI). This apparatus has been manufactured by Spinlab, Inc., and is now manufactured by Zellweger Uster, Inc. in Knoxville, Tenn.
The tapered beard is then subjected to analysis. For example, an instrument known as a Fibrograph, formerly manufactured by Spinlab, Inc., and now by Zellweger Uster, Inc. in Knoxville, Tenn., is employed to optically determine various characteristics of the tapered beard, including the profile along its length. In addition, a separate test may be made of the strength of the tapered beard.
In some respects, the sample as taken by a Hertel needle sampler and the measurement of length and strength therefrom, are worldwide standards.
The approach just described involves collectively testing, essentially simultaneously, all of the fibers of a sample, assumed to be a representative sample. An alternative approach is to individualize and test single fibers and other textile entities, for example neps and trash. Testing single fiber entities can provide a better analysis. Thus, measuring directly, and at high speed, physical properties of single entities in a fiber sample results in basic measurements which provide more and better information which is needed in modern textile manufacturing. The measurements are more basic because single entities (single fibers, single neps, single trash particles, single microdust particles, etc.) are directly measured rather than indirectly by measuring bulk or bundle properties. Equally importantly, they are more basic because statistical distributions are easily formed with the aid of modern electronics technology.
However, such an approach requires means for individualizing single entities and feeding them one at a time into suitable analysis means for testing. A device for such isolation is generally termed a "fiber individualizer", and is generally so termed herein, although a more precise term is "entity individualizer" since, for purposes of testing, it is necessary to accurately determine the amount of neps and trash in a particular sample, in addition to characteristics of the fibers themselves.
An example of such single entity testing apparatus is disclosed in Shofner U.S. Pat. No. 4,512,060, which discloses what is termed in that patent a microdust and trash machine (MTM), and what has since become known as an advanced fiber information system (AFIS), currently manufactured by Zellweger Uster, Inc. in Knoxville, Tenn.
In one form, the AFIS machine separates fibers and neps into one airstream, and trash into another air stream. Optical-based sensors then measure the individual entities. Individual entities can be analyzed at rates as high as 1000 per second. An AFIS more particularly includes an aeromechanical separator or fiber individualizer; high speed single entity sensors; and a high information rate computer for data collection and analysis.
Improvements to the AFIS, particularly improved sensors where a single sensor analyzes neps, trash and fibers individualized all in one air stream are disclosed in Shofner et al application Ser. No. 07/493,961, filed Mar. 14, 1990, entitled "Electro-Optical Methods and Apparatus for High Speed, Multivariant Measurement of Individual Entities in Fiber or Other Samples", and in Shofner et al continuation-in-part applications Ser. No. 07/762,905, filed Sep. 19, 1991, entitled "Apparatus for Monitoring Trash in a Fiber Sample", and Ser. No. 07/962,898, filed Oct. 16, 1992, entitled "Apparatus and Method for Testing Multiple Characteristics of Single Textile Sample with Automatic Feed."
Individualized fibers may be tested, however in a number of other ways, and the fiber individualizers of the present invention are not limited to any particular testing technique. For example, individualized fibers may simply be spread out on a horizontal surface which comprises a contrasting background, and optically imaged.
The fiber individualizer portion of an AFIS, such as is disclosed in U.S. Pat. No. 4,512,060, includes a cylindrical rotating beater wheel having projections which engage fibers of fibrous material fed to the beater wheel for testing. The beater wheels rotates at typically 7,500 rpm, with a circumferential velocity of 5,000 FPM, and is similar to the licker-in of a conventional carding machine, or the beater stage of an open-end spinning head, with the exception that the AFIS beater wheel includes perforations which allow radially inward airflow.
One disadvantage of the fiber individualizer disclosed in U.S. Pat. No. 4,512,060 is that fibers are subject to breakage as they are fed from a fibrous mass and abruptly engaged by the pins of the rotating beater wheel. In particular, fiber damage is caused by the interaction of fiber held between a feed plate/feed roll arrangement and the pinned cylinder rotating at high speed. The resultant action does liberate single fibers from the sample fiber mass but it also causes fiber breakage, and breaks up some foreign matter in the fiber (i.e. cotton trash). This action of restraining a portion of the fiber while quickly accelerating another portion of the fiber is well represented in mill processes (especially in opening, cleaning and carding), and leads to similar problems. Further damage results as fibers, in relatively random orientations, are carried past card flats.
The damage is, in general, more pronounced in a sample containing randomly oriented, highly entangled fibers (bale stock or card mat) than it is in a sample containing disentangled, parallel oriented fibers (sliver). Thus, it has been observed that, when parallelized fibers, such as sliver, are fed to the rotating beater wheel of an AFIS, far less fiber breakage occurs. However, bulk fiber for testing is generally not available in parallelized form.
Another disadvantage of the AFIS Fiber Individualizer is that it requires an elongated, sliver-like sample. For testing fibrous masses, wherein the fibers are randomly oriented, this elongated sample must be currently hand-formed. It follows that alternative means for collecting representative samples and introducing them into AFIS is needed. This need is rapidly increasing now, as automation requirements increase.
Several processes are known for parallelizing fibers, and an important one of such process is known as drafting or drawing, which particularly is employed in production environments, not in testing environments and not for randomly oriented fibrous masses.
Other forms of drafting are known, such as apron drafting or Casablanca drafting wherein a web of fibers, already parallelized and partially drafted, is transported between a pair of belt-like moving aprons and then through a pair of rollers turning at a higher speed. In some situations, such as is disclosed in U.K. Pat. No. 1,242,171, fibers are released from the roller pair essentially one at a time into an airstream.